Oxidative stress is defined as a disturbance in the balance between the production of reactive oxygen species (ROS) and antioxidant defenses (Finkel and Holbrook 2000), (Kunwar et al, 2011).
ROS are molecules containing oxygen reactive molecules; examples of ROS include free radicals, oxygen ions and peroxides.
ROS are formed as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling and homeostasis.
ROS may also act by driving several molecular pathways that play important roles in different pathologic conditions such as cancer, heart diseases and diabetes.
The over-production of peroxides and free radicals leads to damage in the components of the cell, including proteins, lipids and DNA. Moreover, some ROS may act as cellular messengers in reduction/oxidation (redox) signaling between cells. Therefore, oxidative stress can cause disruptions in normal mechanisms of cell signaling.
Thus, the use of oxygen by cells of aerobic organisms generates potentially deleterious reactive oxygen metabolites.
The amount of oxidative damage can increase with the age of an organism and it can be a major factor able to cause senescence (Sohal and Weindruch 1996).
The main point emerging from research studies is that molecular oxidative damage during aging is ubiquitous, significant and increases exponentially with age.
The main causes of an age-associated increase in the amount of oxidative stress can be linked to an increase in the rate of generation of reactive oxygen metabolites (ROMs), a decline in anti-oxidative defenses, a decline in the efficiency of repair or removal of damaged molecules.
Hydrogen peroxide production by mitochondria is also one of the main sources of oxidative stress and in mammals increases with age in several different organs (Turrens and McCord 1990).
A recent study has investigated the effect of gender, age and treatment time on brain oxidative stress and spatial memory deficits induced by d-galactose (d-gal) in mice. Female mice did not show spatial memory impairment, even in the presence of increased amounts of brain reactive oxygen species (ROS). In contrast, male mice receiving the same amount of d-gal showed spatial memory deficits and significant increase in oxidative stress markers (Hao et al, 2014).
Interestingly, another recent study published in 2014, recruited a total of 478 workers (272 men and 206 women) from a coke oven plant. The study found that women were more susceptible than men to oxidative stress and chromosome damage induced by polycyclic aromatic hydrocarbons (PAHs), which adds potential evidence underlying gender differences in PAH exposure-related lung carcinogenesis (Guo et al, 2014).
The skin, together with hair and nails, is the main organ of the integumentary system, and represents the first and main barrier to the external environment.
In the skin, free radical damage can cause deterioration of the supportive connective tissue, resulting in decreased elasticity and resilience. Oxidative stress, moreover, may impair hair follicle function, causing androgenetic alopecia (pattern baldness) in men and women.
Skin exposure to solar ultraviolet radiation initiates photochemical reactions which lead to ROS formation and when their production gets out of control, oxidative stress occurs. When this happens, ROS (together with enzymes released from granules within the white blood cells) injure or even kill cells, damage DNA and attack enzymes and other compounds.
The skin possesses defense mechanisms which interact with toxicants and counteract their deleterious effect (such as non-enzymatic and enzymatic molecules that function as potent antioxidants).
These defenses, although highly effective, have limited capacity and can be overwhelmed leading to increased ROS levels and to the development of dermatological diseases.
It is generally agreed that there is a correlation between ageing and the accumulation of oxidatively damaged proteins, lipids, and nucleic acids (Levine and Stadtman 2001).
A recent study has shown that exposure of skin to a number of chemical and physical environmental agents induces oxidative stress that leads to the induction of cutaneous lipid peroxidation with concomitant modulation in the levels of antioxidant and drug-metabolizing enzymes.
One approach to prevent or treat these ROS-mediated disorders is based on the administration of different antioxidants wherein the term antioxidant refers to any molecule capable of stabilizing or deactivating free radicals before they cause damage in healthy cells.